Spinal fusion is a procedure that involves joining two or more adjacent vertebrae with a spinal fixation device to restrict movement of the vertebra with respect to one another. For a number of known reasons, spinal fixation devices are used in spine surgery to align and/or fix a desired relationship between adjacent vertebral bodies. Such devices typically include a pair of spinal fixation elements, such as, for example, a relatively rigid fixation rod, a dynamic or flexible spinal rod, a plate, etc., longitudinally placed on the posterior spine on either side of spinous processes of the vertebral column. The spinal fixation elements being coupled to adjacent vertebrae by attaching the spinal fixation element to various bone fixation elements, such as, for example, hooks, bolts, wires, screws, etc. The bone fixation elements commonly include body portions with rod-receiving channels in which the spinal fixation element is inserted and subsequently clamped. Surgeons may commonly choose to install multiple bone fixation elements, as well as multiple spinal fixation elements, to treat a given spinal disorder.
The spinal fixation elements may have a predetermined contour, and once installed, the spinal fixation element may hold the vertebrae in a desired spatial relationship, either until desired healing or spinal fusion has taken place, or for some longer period of time.
It is also well known that the strength and stability of dual spinal rod assemblies can be increased by coupling the two spinal rods with a cross-brace or transconnector which typically extends substantially transverse to the spinal rods and typically substantially horizontally across the spine to interconnect the longitudinal spinal rods. The use of transconnectors, however, can provide surgeons with one or more difficulties. The simplest situation in which a transconnector could be used occurs when the two spinal rods are substantially parallel to each other, i.e. there is no rod convergence or divergence in the medial-lateral direction; where the two spinal rods have the same orientation with respect to the coronal plane viewed in the anterior-posterior direction, i.e. the spinal rods are coplanar from a lateral view; and where the two spinal rods are located at a fixed, predetermined distance from each other. However, due to a wide variety of factors, the two spinal rods are rarely so geometrically aligned in clinical situations.
Thus, it is advantageous to provide a transconnector which may be adjusted to adapt to variations in spinal rod alignment. The addition of such adjustability, however, may require the transconnector to include numerous pieces that can be difficult to assemble and use while in the surgical environment.
Furthermore, when transconnectors are placed over adjacent spinal rods, the extended profile of the device may often result in soft tissue trauma. Thus, it is advantageous to provide a transconnector with as small a lateral (i.e., transverse) profile as possible to decrease the total amount of soft tissue trauma incurred, and to minimize the chance for subsequent complications. Providing a transconnector with a small lateral profile is also beneficial when attempting to engage longitudinal spinal rods wherein, for one reason or another, the bone fixation elements are closely spaced together.
It is further advantageous to provide a transconnector that, once assembled, prevents disassembly of the individual pieces of the transconnector assembly, thereby helping to facilitate installation of the transconnector by reducing the likelihood that the transconnector will accidentally come apart during installation in the patient. It is also advantageous to provide a transconnector that reduces the overall number of steps required to fix the location of the transconnector with respect to the longitudinal spinal rods, thereby facilitating installation of the transconnector by reducing the time and effort needed for installation in the patient.
Thus, there exists a need for an improved transconnector for coupling adjacent spinal rods which advantageously may be adapted to adjust to varying spinal rod alignments, which has a reduced lateral footprint for reducing associated tissue trauma and which when pre-assembled will remain intact during installation in the patient.